1. Field of the Invention
The present invention relates to an oil-soluble derivative of a glycosyl-L-ascorbic acid, and more particularly to an acyl derivative of a glycosyl-L-ascorbic acid.
2. Description of the Prior Art
Vitamin C or L-ascorbic acid, an anti-scorbutus factor, has been widely used as a specific medicine for scorbutus. At present, it is revealed that vitamin C deeply correlates to hydroxyl reactions in vivo, for example, the biosynthesis of collagen, the metabolism of aromatic amino acids, and the formation of adrenalin in the adrenal; and it also plays an important role in the detoxification system for external invaders in the liver. Because of these diversified physiological activities, a quantity of L-ascorbic acid is consumed annually in the food-, cosmetic-, and pharmaceutical-fields.
As it is well known, unlike other vitamins, L-ascorbic acid is a relatively-highly unstable substance easily decomposed or denatured by heat, light, oxygen, metal ions, etc. Therefore, users must use L-ascorbic acid in a higher amount that far exceeds a theoretical level, and must pay close attention to the storing and handling of the compound. Also there exists a problem that L-ascorbic acid could not reach the desired tissues in a desired effective amount because it is not oil-soluble and the permeation to the tissues is inhibited by fat components when applied to in vivo tissues such as skin and mucosas rich in fat components. To overcome these drawbacks, many efforts have been made to convert L-ascorbic acid into its acid esters and glycosyl compounds.
Although conventional fatty acid esters such as 2-stearyl-L-ascorbic acid, 6-palmityl-L-ascorbic acid, and 2,6-dipalmityl-L-ascorbic acid have an improved oil-solubility oven intact L-ascorbic acid, these esters do not release L-ascorbic acid in vivo and could not exert the important physiological actions of L-ascorbic acid. Similar to intact L-ascorbic acid, inorganic esters of L-ascorbic acid such as phosphates and sulfates of L-ascorbic acid have the following problems; they are not oil-soluble, and in particular, these sulfates and fatty acid esters do not release L-ascorbic acid in vivo.
Glycosyl-L-ascorbic acids such as 2-O-glucopyranosyl-L-ascorbic acid and 2-O-galactopyranosyl-L-ascorbic acid, as disclosed in Japanese Patent Kokai Nos. 139,288/91, 135,992/91, 183,492/91, 228,183/94, and 263,790/94, are substances that were explored to overcome the drawbacks of L-ascorbic acid. These L-ascorbic acid derivatives have no reducing group within their molecules so that they have an extremely-high tolerance to heat, light, oxygen, and metal ions, and have a character of easily releasing L-ascorbic acid in vivo. Depending on use, the conventional L-ascorbic acid derivatives, however, have drawbacks similar to L-ascorbic acid due to their non-oil-solubility.
L-Ascorbic acid is a natural compound distributed widely in plants and animals, and is present in animals' adrenals and citrus fruits, and therefore it can be advantageously used in food products, cosmetics, and pharmaceuticals with lesser side effects. Recently, radicals formed in living bodies are known as a factor for life-style related diseases or geriatric diseases, in this regards L-ascorbic acid is said to have an activity of entrapping radicals in vivo and is capable of preventing the generation of tumor cells. It is highly speculated that the demands and uses of L-ascorbic acid will be widened more and more.